#decoratorpattern

In plain words, the Decorator pattern lets you dynamically change the behavior of an object at run time by wrapping it in an object of a decorator class. Decorators provide a flexible alternative to subclassing for extending functionality.

Let's make a quick and simple example with coffee and PHP!

First of all, we define a CoffeeInterface:

interface CoffeeInterface { public function getCost(); public function getDescription(); }

And now we create a SimpleCoffee class that implements the CoffeeInterface:

class SimpleCoffee implements CoffeeInterface { public function getCost() { return 10; } public function getDescription() { return 'Simple coffee'; } }

But what would happen if we took a coffee with milk or with chocolate or with both? If we create a concrete implementation for each, it will be very tedious to manage. And how could we handle a thousand of different kinds of coffee? That is where we can use the Decorator pattern! With that pattern, we can easily manage a coffee with milk and chocolate or with something else.

So, we have a coffee with milk:

class MilkCoffee implements CoffeeInterface { protected $coffee; public function __construct(CoffeeInterface $coffee) { $this->coffee = $coffee; } public function getCost() { return $this->coffee->getCost() + 2; } public function getDescription() { return $this->coffee->getDescription() . ', milk'; } }

...and with chocolate:

class ChocolateCoffee implements CoffeeInterface { protected $coffee; public function __construct(CoffeeInterface $coffee) { $this->coffee = $coffee; } public function getCost() { return $this->coffee->getCost() + 4; } public function getDescription() { return $this->coffee->getDescription() . ', chocolate'; } }

And we use them like so: